1. Field of the Invention
The present invention relates to a method for forming a microcrystalline semiconductor film and a method for manufacturing a semiconductor device including the microcrystalline semiconductor film. Further, the present invention relates to a method for forming a semiconductor film and a method for manufacturing a semiconductor device including the semiconductor film.
In this specification, a semiconductor device refers to all the devices that can operate by utilizing semiconductor characteristics. A thin film transistor in this specification is a semiconductor device; and a display device, a semiconductor circuit, and an electronic device including the thin film transistor are all semiconductor devices.
2. Description of the Related Art
As one type of field-effect transistor, a thin film transistor (also referred to as a TFT) whose channel region is formed in a semiconductor film which is formed over a substrate having an insulating surface is known. A technique in which a microcrystalline semiconductor film having a higher field-effect mobility than an amorphous semiconductor film is used as the semiconductor film in the thin film transistor has been disclosed (see Patent Document 1). A technique in which the semiconductor film is formed using silane (SiH4) which is diluted with hydrogen and a rare gas element, for example, has been disclosed (see Patent Document 2).
Typical examples to which the thin film transistor is applied are flat panel displays such as liquid crystal display devices and light-emitting display devices, in which the thin film transistor is practically used as a switching transistor in each pixel in a display screen.